Extreme hunting efficiency in a carnivorous bat

Large predators typically hunt relatively large prey, with high failure rates and energetic costs. In contrast, small predators generally hunt relatively small, abundant prey at lower failure rates, incurring relatively lower costs. Many bats are small predators with high metabolic rates during flight, and most species hunt large numbers of abundant, small insects. However, nine different bat species have evolved true carnivory, targeting large, less-abundant vertebrate prey. This rare behavior poses a paradox: how can such small predators, with limited energy stores and high absolute energy requirements, sustain a hunting strategy that typically involves prolonged searching and high-energy chases with low success? We address this question by quantifying the hunting behavior of 20 wild carnivorous fringe-lipped bats (Trachops cirrhosus) with sound and movement biologging tags. The median estimated prey size of ∼2 g corresponds to roughly 7% of the bats’ body mass. However, long mastication times of up to 84 min after a kill indicate that they can target prey approaching their own body size of 30 g. Unlike much larger predators, they hunt with extreme efficiency: bats spent only a fraction of the night in flight (median 11%, quartiles 7%–14%) and complemented short search and pursuit times with high hunting success rates (median 50%, quartiles 35%–62%), capitalizing on eavesdropping on prey sounds and ambush predation. This unusual low-risk/high-gain strategy relies on high prey densities in pristine ecosystems, raising concerns for the Anthropocene fate of these specialized predators.

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